This study review changes and differences in perinatal mortality for similar populations over a period of rapid change in technology, use of cesarean sections, and medical management of high risk pregnancies. Data sources include previously unpublished data from 1970-81 for fetal deaths from the National Center for Health Statistics, and perinatal and infant mortality from 1975-84 based on states participating in a current study of multinational birth weight-specific perinatal mortality rates supported with research contract funds.